Pencil lead



Patented vlAug.l 13,"A 1935 PATENT' 'OFFICE amare rauen. LEAD I sidor Chesler, West'Orange, N. J., assignor to Eagle Pencil Company, New York, N. Y., a corporation of Delaware r Application July 6, 1934, Serial 4 Claims. (Cl. 12o- 83) 4 cave as at IZ'between consecutive pairs, and at l My present invention is concerned with pencil eads.

An object of the invention is to provide a pencil lead which, though of small diameter, with- 5 out the need for pointing or sharpening the lead,

is adapted to make a marking line surprisingly thiri and sharp, compared to the diameter of the lea f Another object is to provide a lead of the above type of' universal applicability for various types of wooden and mechanical pencils now onl the market, and which in' the'use of such pencils ailords the specialized utility. above alluded to.

. Another object is to provide a lead of the above type, in which the above utility is attained, though `the lead be solid in cross-section, .as is a conventional lead, and is made of the -conventional lead mix of filler, binder and graphite or pigment.

Another object is to provide a lead of the above y type, by which the likelihood of breakage in the process of insertion of the lead into a mechanical pencil is minimized, without sacrifice in the security with which the lead is held in the mechanical pencil. Y

In the accompanying drawing, in 4which` is shown one of various possible embodiments of the several features of the invention,

Fig. 1 is a side view of my preferred lead,-

Fig. 2 is a view in longitudinal cross-section of the lead, on a greatly enlarged section, and

Fig. 3 is a view partly in cross-section showing the lead applied in one construction of mechanical pencil.

The invention in general comprises the use of a lead having a cross-section generally polygonal with an even number of lsides alternately of greater and lesser length, the surface of the lead being depressed or concave between consecutive edges, which edges are equidistant from the axis of the lead.'

In the accompanying drawing is shown a preferred embodiment of the invention in winch the lead is generally octagonal in cross-section.V The edges extend in pairs adjacent toeach other, one pair being shown at Il' and each pair being separated from the neighboring pair by an interval greater than between the elements of the pair.

In a preferred embodiment, the edges arel spaced by angular intervals, alternately yof 30 degrees and 60 degrees, as shown. Each pair of edges thus extends in a plane parallel to'the opposite pair of adjacent edges. As shown, the surface of the lead is depressed or rendered con- I3 between each pair of edges.

In the preferred specific embodiment, all edges I are at a uniform distance from the axis Il of the lead, incommercial practice for ordinary mechanical pencils, preferably .023 inches. The

concavity of each llonger face of the lead may be as shown in the drawings von a radius of .049 inches and of .010. inches for the shorter faces. It is noted that the edges i0 while sharp are determined by areasintersecting each other almost at right angles,`and, accordingly, the edges have considerable mechanical strength compared to edges at sharply acute angles.

The lead is formed by extrusion in the conventional way, except that the die has the crosssection shown'in Fig. 2, instead of the conventional circular cross-section.

In Fig. 3 is shown a cross-section of mechanical pencil equipped with the lead just described. It is seen that the lead described is4 more easily engaged within the lead holding clutch I5 than is the ordinary round lead, for it engages such clutch only at some or all of the eight sharp points or apices Iii' as it is inserted, and any non-uniformity in either the lead or the clutch will not result in breaking -of the lead, since the sharp apices will more readily wear off in the process of inserting the lead than would the entire periphery'of an oversized or incorrectly` centered circular lead` The same considerations apply from the standpoint of feeding the lead in use through the tapered point i6 of the mechanical pencil.

The details of4 the mechanical pencil illustratively shown in Fig. 3 need not be described for this is merely one of numerous possible conventional constructions in which the rear end'of the lead is held by the clutch sleeve I5, which has a wing or offset I1 riding within a threaded track I8 within the pencil casing I9 and is operated by means (not shown) preferably from the eraser end 20 of the pencil.

Only a point or apex lilpcan touch the paper for writing; the depressed or concave surfaces I2 and I3, even though the pencil is butin the neighborhood of a 20th of an inch in diameter, cannot possibly reach the paper until the point or apex has been worn down. In ordinary use, the apices at the tip of the lead will all be worn down more or less uniformly and they must be worn down prac- .tically to their roots before the concavities I2 and Il, which noware no longer concavities can touch the paper, and by then, the point of the pencil will have been worn down to so small a diameter that` the writing line will be approximately as thin as 'could be made-by one of the sharp apices. A new and complete, generally octagonal cross-sectional area of lead is now exposed for service, for repetition of the wearing action incurred in writing, as just set forth. l

inasmuch as all of the edges of my lead are equi-distant from the axis of the pencil, they lie on a cylindrical locus and, accordingly, the lead is applicable to any and all mechanical pencils designed primarily for a circular lead and with all of the advantages above set forth in the use of the specialized form of lead described.

It will thus be seen that there is herein described an article in which the several features of this invention are embodied, and which article in its action attains the various objects of the invention and is well suited to meet the requirements of practical use.

As many changes could be made in lthe above article, and many apparently widely dierent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not nally thereof and equidistant from the axis of said lead, said edges distributed peripherally of the lead in a plurality of pairs of contiguous edges, the pairs ofadjacent edges being separated by a distance greater than the distance between the edges of any one of said pairs, the surface of the lead between each pair of said edges and the consecutive pair of said edges being concave.

2. A pencil lead generally polygonal in crosssection, having an even number of sides, and edges, each pair of edges in a plane parallel to another pair of edges, said edges distributed in an even number of pairs of adjacent, parallel edges, each pair separated from the neighboring pair of edges by a distance greater than the'distancel between the edges of any one pair, the faces of said lead being concave between consecutive l edges.

3. A pencil lead having a cross-section polygonal in shape with an even number'of edges, all equidistant from the axis of the lead, said edges distributed in an even number of pairs, the members of each pair spaced from each other by a constant angular interval, the angular interval between consecutive pairs being twice that between the members of each pair of edges, the lead being concave between consecutive edges.

4. A pencil lead generally octagonal in crosssecton with sharp edges equidistant from'the axis of the lead, said edges spaced from each other by alternate angles of 30 degrees and 60 degrees, and the surface of the lead being concave between consecutive edges.

ISIDOR CHESLER. 

